CONCRETE CONTRACTOR LICENSING EXAMINER EXAM QUESTIONS AND
ANSWERS (VERIFIED ANSWERS) PLUS RATIONALE 2025/2026 Q&A/
INSTANDOWNLOAD PDF
1. What is the typical minimum compressive strength of concrete used for residential slabs?
A. 1500 psi
B. 2500 psi
C. 3500 psi
D. 5000 psi
Correct answer: B. 2500 psi
Rationale: Most residential slabs are designed for 2500–3000 psi compressive strength for
adequate durability and load capacity.
2. Which of the following aggregates provides the best workability in concrete?
A. Angular coarse aggregate
B. Rounded river gravel
C. Crushed granite
D. Sand only
Correct answer: B. Rounded river gravel
Rationale: Rounded aggregates improve workability by reducing internal friction among
particles.
3. What is the ideal water-cement ratio for durable concrete?
A. 0.25
B. 0.40
C. 0.60
D. 0.80
Correct answer: B. 0.40
Rationale: A water-cement ratio around 0.40 achieves a good balance between strength and
workability.
4. What is the main purpose of air entrainment in concrete?
A. To increase density
B. To reduce shrinkage
,C. To improve freeze–thaw resistance
D. To accelerate setting
Correct answer: C. To improve freeze–thaw resistance
Rationale: Air-entrained concrete has tiny air bubbles that relieve pressure from freezing water
expansion.
5. What happens if too much water is added to concrete?
A. Strength increases
B. Shrinkage decreases
C. Durability improves
D. Strength decreases
Correct answer: D. Strength decreases
Rationale: Excess water increases porosity, reducing the ultimate compressive strength.
6. What is the main purpose of using rebar in concrete?
A. To prevent surface cracking
B. To resist tensile stresses
C. To make concrete lighter
D. To accelerate curing
Correct answer: B. To resist tensile stresses
Rationale: Concrete is strong in compression but weak in tension; rebar provides tensile
strength.
7. Which cement type is best for structures exposed to sulfate attack?
A. Type I
B. Type II
C. Type IV
D. Type V
Correct answer: D. Type V
Rationale: Type V cement has high sulfate resistance for use in sulfate-rich soils or
groundwater.
8. What is the recommended minimum curing period for normal concrete at 20°C (68°F)?
A. 1 day
B. 3 days
C. 7 days
D. 14 days
, Correct answer: C. 7 days
Rationale: Seven days of moist curing allows sufficient hydration for most structural concrete.
9. Which test measures concrete’s workability?
A. Compressive strength test
B. Slump test
C. Air content test
D. Core test
Correct answer: B. Slump test
Rationale: The slump test indicates the consistency and workability of freshly mixed concrete.
10. What is the primary cause of honeycombing in concrete?
A. Over-vibration
B. Insufficient vibration
C. Excess cement
D. High water content
Correct answer: B. Insufficient vibration
Rationale: Poor compaction leaves voids between aggregate particles, leading to honeycombing.
11. Which of the following admixtures reduces water content while maintaining workability?
A. Retarder
B. Superplasticizer
C. Accelerator
D. Air-entraining agent
Correct answer: B. Superplasticizer
Rationale: Superplasticizers enhance flow without extra water, maintaining strength.
12. What is the main cause of concrete scaling?
A. Insufficient curing
B. Over-vibration
C. Freeze–thaw cycles
D. High slump
Correct answer: C. Freeze–thaw cycles
Rationale: Repeated freezing and thawing causes surface peeling when air entrainment is
inadequate.
ANSWERS (VERIFIED ANSWERS) PLUS RATIONALE 2025/2026 Q&A/
INSTANDOWNLOAD PDF
1. What is the typical minimum compressive strength of concrete used for residential slabs?
A. 1500 psi
B. 2500 psi
C. 3500 psi
D. 5000 psi
Correct answer: B. 2500 psi
Rationale: Most residential slabs are designed for 2500–3000 psi compressive strength for
adequate durability and load capacity.
2. Which of the following aggregates provides the best workability in concrete?
A. Angular coarse aggregate
B. Rounded river gravel
C. Crushed granite
D. Sand only
Correct answer: B. Rounded river gravel
Rationale: Rounded aggregates improve workability by reducing internal friction among
particles.
3. What is the ideal water-cement ratio for durable concrete?
A. 0.25
B. 0.40
C. 0.60
D. 0.80
Correct answer: B. 0.40
Rationale: A water-cement ratio around 0.40 achieves a good balance between strength and
workability.
4. What is the main purpose of air entrainment in concrete?
A. To increase density
B. To reduce shrinkage
,C. To improve freeze–thaw resistance
D. To accelerate setting
Correct answer: C. To improve freeze–thaw resistance
Rationale: Air-entrained concrete has tiny air bubbles that relieve pressure from freezing water
expansion.
5. What happens if too much water is added to concrete?
A. Strength increases
B. Shrinkage decreases
C. Durability improves
D. Strength decreases
Correct answer: D. Strength decreases
Rationale: Excess water increases porosity, reducing the ultimate compressive strength.
6. What is the main purpose of using rebar in concrete?
A. To prevent surface cracking
B. To resist tensile stresses
C. To make concrete lighter
D. To accelerate curing
Correct answer: B. To resist tensile stresses
Rationale: Concrete is strong in compression but weak in tension; rebar provides tensile
strength.
7. Which cement type is best for structures exposed to sulfate attack?
A. Type I
B. Type II
C. Type IV
D. Type V
Correct answer: D. Type V
Rationale: Type V cement has high sulfate resistance for use in sulfate-rich soils or
groundwater.
8. What is the recommended minimum curing period for normal concrete at 20°C (68°F)?
A. 1 day
B. 3 days
C. 7 days
D. 14 days
, Correct answer: C. 7 days
Rationale: Seven days of moist curing allows sufficient hydration for most structural concrete.
9. Which test measures concrete’s workability?
A. Compressive strength test
B. Slump test
C. Air content test
D. Core test
Correct answer: B. Slump test
Rationale: The slump test indicates the consistency and workability of freshly mixed concrete.
10. What is the primary cause of honeycombing in concrete?
A. Over-vibration
B. Insufficient vibration
C. Excess cement
D. High water content
Correct answer: B. Insufficient vibration
Rationale: Poor compaction leaves voids between aggregate particles, leading to honeycombing.
11. Which of the following admixtures reduces water content while maintaining workability?
A. Retarder
B. Superplasticizer
C. Accelerator
D. Air-entraining agent
Correct answer: B. Superplasticizer
Rationale: Superplasticizers enhance flow without extra water, maintaining strength.
12. What is the main cause of concrete scaling?
A. Insufficient curing
B. Over-vibration
C. Freeze–thaw cycles
D. High slump
Correct answer: C. Freeze–thaw cycles
Rationale: Repeated freezing and thawing causes surface peeling when air entrainment is
inadequate.
